OBJECTIVE: In accordance with Boyle's law (as barometric pressure decreases, gas volume increases), thoracostomy is often recommended for patients with pneumothoraces before helicopter EMS (HEMS) transport. We sought to characterize altitude-related volume changes in a pneumothorax model, aiming to improve clinical decisions for preflight thoracostomy in HEMS patients. METHODS: This prospective study used 3 devices to measure air expansion at HEMS altitudes. The main device was an artificial pneumothorax model that mimicked a human pulmonary system with a 40 mL pneumothorax. In addition, volume changes were calculated in 2 spherical balloons (6 L and 25 L) by measuring equatorial circumferences. Measurements were recorded at 500-foot altitude increments from 1000 to 5000 feet above ground level. RESULTS: The 3 models exhibited volume increases of 12.7%-16.2% at 5000 feet compared to ground level. Univariate linear regression yielded similar increases, 1.27%-1.52%, in volume per 500-foot altitude increase for all 3 models. Bivariate indexed linear regression identified no association between volume increase and assessment model (P values .19 and .29). Locally weighted scatterplot smoothing (lowess) plots indicated linearity of the altitude-volume relationship. CONCLUSION: This study demonstrated predictable pneumothorax volume changes at typical HEMS altitudes. Increased understanding of altitude-related volume changes will aid decision making before transport.
OBJECTIVE: In accordance with Boyle's law (as barometric pressure decreases, gas volume increases), thoracostomy is often recommended for patients with pneumothoraces before helicopter EMS (HEMS) transport. We sought to characterize altitude-related volume changes in a pneumothorax model, aiming to improve clinical decisions for preflight thoracostomy in HEMS patients. METHODS: This prospective study used 3 devices to measure air expansion at HEMS altitudes. The main device was an artificial pneumothorax model that mimicked a human pulmonary system with a 40 mL pneumothorax. In addition, volume changes were calculated in 2 spherical balloons (6 L and 25 L) by measuring equatorial circumferences. Measurements were recorded at 500-foot altitude increments from 1000 to 5000 feet above ground level. RESULTS: The 3 models exhibited volume increases of 12.7%-16.2% at 5000 feet compared to ground level. Univariate linear regression yielded similar increases, 1.27%-1.52%, in volume per 500-foot altitude increase for all 3 models. Bivariate indexed linear regression identified no association between volume increase and assessment model (P values .19 and .29). Locally weighted scatterplot smoothing (lowess) plots indicated linearity of the altitude-volume relationship. CONCLUSION: This study demonstrated predictable pneumothorax volume changes at typical HEMS altitudes. Increased understanding of altitude-related volume changes will aid decision making before transport.
Authors: Nirav Dhanesha; Thomas Schnell; Salam Rahmatalla; Jonathan DeShaw; Daniel Thedens; Bradley M Parker; M Bridget Zimmerman; Andrew A Pieper; Anil K Chauhan; Enrique C Leira Journal: Stroke Date: 2020-05-13 Impact factor: 7.914
Authors: G Sumann; D Moens; B Brink; M Brodmann Maeder; M Greene; M Jacob; P Koirala; K Zafren; M Ayala; M Musi; K Oshiro; A Sheets; G Strapazzon; D Macias; P Paal Journal: Scand J Trauma Resusc Emerg Med Date: 2020-12-14 Impact factor: 2.953